1. Field of the Invention
The present invention provides a system for conveying containers from a first location to a second location, the containers being marked at the first location with a magnetic pulse, the magnetic pulse being detected at the second location using a magnetic sensing device.
2. Description of the Prior Art
Systems for conveying containers from a first location whereat a selected container is marked, or encoded, to a second location wherein the selected container is identified based on the markings thereon have been available for many years. Typically, containers are marked with visible indicia and the container detected using a light source, optics, photodector and electronic processing circuitry. One of the problems inherent in the prior art systems is that the technique used to produce visual indicia marking requires consumables, which in addition to the expense, is messy, causes system clogging, etc. In addition, the optically based detection systems need frequent maintenance to keep the conveyor system operating efficiently.
Further, In addition, it is particularly difficult to track a single container (can or bottle) on a conveyor system, the container being marked at one location and typically rejected at a second location downstream without losing track of the marked container. Various prior art detecting systems are disclosed in U.S. Pat. Nos. 4,914,964 to Speiser (system for measuring the alignment between two moving targets); U.S. Pat. No. 5,335,777 to Murphy et al (apparatus for tracking data associated with a conveyor belt load being conveyed from a first station to a spaced apart second station); U.S. Pat. No. 4,249,661 to Lem (apparatus for sorting various loads, code being first imprinted or otherwise affixed to the item and read downstream by conventional optical and magnetic means); and U.S. Pat. No. 3,696,946 to Hunter et al (automatic conveyor system to monitor the position of the conveyor carrier and to cause a carrier to unload its contents when it reaches an appropriate receiving bin).
Hall effect devices (as is well known, the Hall effect describes the disturbance of the lines of current flow in a conductor due to the application of a magnetic field, resulting in an electric potential gradient transverse to the direction of current flow) have been used in various system processes. For example, Hall effect devices have been used to determine the level of liquid in containers (see for example, U.S. Pat. No. 5,565,687). U.S. Pat. No. 5,793,200 discloses a position sensing system which utilizes a magnet to actuate a detecting array of solid state Hall effect devices.
The use of Hall effect sensors, or decoders, provides significant advantages in that the detector (single or in an array) is less costly than optical based detector systems, are more accurate and reliable, and most importantly, the detection process is insensitive to the conveyor speed thus minimizing the possibility of detection error. However, any other magnetic sensing device may be used, particularly if the conveyor is one that runs at constant speed. The Hall effect device can also detect different levels of magnetic strength.
The inventor of the present invention is unaware of any conveyor belt system which has utilized a magnetic sensing device, such as Hall effect devices, to detect a magnetically coded item transported on a conveyor belt from one location to another remote location.
What is thus desired is to provide a marking technique for a bottle or can conveyor system wherein the mark is readable for extended periods of time subsequent to the marking and wherein the marked item is detected downstream using a simple and cost efficient detector device. For example, this marking technique should be capable of being used to mark containers from specific filler valves or capper heads so they can be detected and rejected downstream for quality control evaluation purposes. Production lines typically run so fast that this process cannot be carried out manually.